Most mobile machines include an operator cabin having a controlled environment that increases operator comfort. For example, the operator cabin can be heated or air conditioned to maintain the operator cabin at a desired temperature. When a machine is new, environmental control components within the operator cabin (e.g., an air conditioning unit or a heating unit) function at peak performance and easily maintain the desired temperature within the operator cabin. Over time, however, the performance of these components degrade, and it may become difficult or even impossible for the desired temperature to be maintained under all conditions. In these situations, the machines may need to be serviced in order to return performance of the environmental control components to previous levels. Unfortunately, this service may be disruptive and costly to the machine owner.
Mobile machines are often caused to idle for long periods of time. For example, the machines may idle overnight when the operator is resting and the machine's engine is being used to power the environmental control components. In some locations, however, idling for long periods of time may not be allowed for environmental reasons. In these situations, the machines must be turned off, resulting in ambient conditions within the operator cabin that are uncomfortable for the operator. And even if long periods of idling are allowed, doing so can be inefficient and costly.
One attempt to address one or more of the problems described above is disclosed in U.S. Pat. No. 5,333,678 that issued to Mellum et al. on Aug. 2, 1994 (“the '678 patent”). In particular, the '678 patent describes a machine having an auxiliary power unit that can be used to selectively power and control environmental conditions within an operator cabin of the machine when a main engine and associated main air conditioning components of the machine are turned off. The auxiliary power unit includes an auxiliary engine that is smaller than the main engine, and auxiliary air conditioning components driven by the auxiliary engine.
Although using the auxiliary power unit of the '678 patent may help to avoid long idling periods of a machine's main engine, the auxiliary power unit may still be problematic. In particular, the auxiliary power unit, because of its numerous duplicative components, may be expensive, complicated to control, and decrease a reliability of the machine. In addition, the auxiliary power unit may have no effect on a capacity of the main air conditioning components to cool the operator cabin during operation of the main engine.
The disclosed cooling system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.